BMW Won’t Start but Battery Is Good: What to do

BMW Won’t Start but Battery Is Good

Trying to start your BMW and getting nothing — even though the battery is fully charged? That’s a common issue, and the good news is, you’re not alone. When your BMW won’t start but the battery is good, the problem usually lies in the ignition system, fuel delivery, starter motor, or a security feature like the immobilizer. Let’s break down what to check, how to diagnose the issue, and what you can do to get your BMW running again.

Why Your BMW Won’t Start Even Though the Battery Is Fine

If your battery has good voltage but the car still won’t start, it’s likely due to:

• Faulty starter motor or starter relay
• Bad ignition switch or push-start system
• Fuel pump failure
• Crankshaft or camshaft position sensor malfunction
• BMW’s immobilizer (EWS or CAS) system blocking ignition

Modern BMWs use advanced modules and sensors to manage every part of the startup sequence. If any single part fails, it can prevent your engine from firing even with a strong battery. For a full look into how BMW tech works together, visit this BMW tech features library.

How to Troubleshoot a No-Start BMW with a Good Battery

Use this quick checklist to narrow down the cause:

1. Check dashboard lights: If they come on normally, your ignition switch is likely fine.
2. Listen for clicking: A click but no crank usually means a bad starter or relay.
3. No sound at all? That could point to a failed ignition switch or immobilizer issue.
4. Cranks but doesn’t start? Then it’s likely a fuel or spark problem.

Don’t just guess. Reading fault codes with a BMW-compatible scanner can often tell you exactly where the issue lies. Want to learn more about how these systems interact? Explore these BMW diagnostic tools and how they work.

Common Causes by Symptom

Symptom	Likely Cause
No crank, lights come on	Starter motor or ignition switch
Cranks but won’t start	Fuel pump, crankshaft sensor, or spark failure
Clicking sound only	Starter solenoid or relay issue
Key turns but nothing happens	Immobilizer (EWS or CAS) preventing ignition

BMW Immobilizer (EWS or CAS) May Be the Issue

BMW’s security system can sometimes prevent the car from starting if there’s a mismatch between your key and the control module. This is especially true if:

• You’ve recently changed the battery or done electrical work
• The key isn’t recognized (try a spare key if you have one)
• You get no crank or just a short blip when turning the key

Resyncing the EWS or CAS system often solves this. Some models require dealer-level tools to reset, but you can learn more about the BMW immobilizer systems in this detailed overview of BMW’s tech features.

What If It’s the Starter or Ignition System?

If your BMW shows all normal lights but doesn’t crank or just clicks, the starter motor or ignition system might be the issue. Try this:

• Tap the starter gently with a wrench while turning the key — sometimes the solenoid sticks.
• Check the starter relay under the fuse box — it may be faulty or loose.
• Test for voltage at the starter — if power is reaching it and it doesn’t spin, it needs replacement.

Fuel System Checks

If your BMW cranks but won’t start, the engine may not be getting fuel. Try the following:

1. Turn the key to “on” and listen for the fuel pump hum (2–3 seconds).
2. If silent, check fuel pump fuse and relay.
3. Scan for fuel pressure using a fuel rail test port if available.

BMW fuel pumps can fail with little warning, especially on models older than 10 years. For detailed guides on BMW fuel and engine systems, this resource page offers excellent tech info.

Can You Jump Start It If Battery Is Good?

Sometimes, yes. If a control module or relay is underpowered, jumping may temporarily fix the problem. But if the battery tests healthy (12.4V+), jumping shouldn’t be necessary — and likely won’t help.

Instead, focus on identifying whether the issue is mechanical (starter), electrical (ignition), or security-based (immobilizer).

Repair Costs for No-Start Issues

Here are average costs for common BMW starting issues:

Component	Estimated Cost
Starter Motor	$300 – $600
Crankshaft Sensor	$200 – $400
Fuel Pump	$400 – $800
Ignition Switch	$150 – $350
EWS/CAS Reset	$150 – $500

When to Call a Professional

Call a BMW specialist or get the car towed if:

• You’ve ruled out the battery, fuses, and relays
• You hear no sound from the fuel pump or starter
• There are immobilizer-related codes like EWS tampering

BMW no-start issues often involve software, so a regular OBD2 scanner may not show the full picture. A shop with BMW-specific tools can scan and reprogram modules if needed.

Conclusion

If your BMW won’t start but the battery is good, the issue is likely with the starter, ignition, fuel system, or anti-theft module. Start by checking for simple clues — sounds, lights, and relays — then scan for fault codes. Getting the right diagnosis saves time, money, and stress.

Want to understand more about how your BMW’s complex systems interact during startup? Browse this expert collection of BMW system explanations and stay ahead of the next issue.